Deep MALDI Mass Spectrometry for Serum Protein Detection
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Solution Overview
Problem
Conventional MALDI-TOF mass spectrometry is limited in detecting proteins in complex biological samples like serum or plasma due to high dynamic ranges of protein abundance, with typical methods only revealing high-abundance proteins and not providing significant information from trace amounts, and the protein content is depleted with excessive laser shots.
Innovation Solution
The 'deep-MALDI' approach involves collecting and averaging hundreds of thousands to millions of shots per MALDI spot, reducing noise and revealing previously invisible peaks, allowing for the detection of a large number of proteins in a semi-quantitative and reproducible fashion by optimizing sample application and automation of spectral acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the number of laser shots is increased beyond 1,000, then more spectral information is revealed and noise is reduced, but the protein content is depleted and the laser and detector are subject to undue wear
Solution Approach 1:
The patent divides the sample analysis into multiple spots on the MALDI plate, each spot receiving a limited number of shots (500-1000). By segmenting the total analysis across multiple spots rather than concentrating all shots on a single spot, the method reveals more spectral information while preventing protein depletion at any individual location.
2Loss of information
If the number of laser shots is increased beyond 1,000, then more spectral information is revealed and noise is reduced, but the laser and detector are subject to undue wear
Solution Approach 1:
The patent segments the total shot count across multiple sample spots, limiting each spot to 500-1000 shots. This distribution strategy achieves comprehensive spectral coverage while maintaining laser and detector lifespan by avoiding excessive cumulative shots at any single location.
3Reliability
If the number of shots per spot is limited to 500-1,000, then protein depletion and instrument wear are prevented, but the detection of low-abundance proteins is insufficient
Solution Approach 1:
The patent applies segmentation by distributing the analysis across multiple spots, where each spot is analyzed with 500-1000 shots. This approach maintains reliability for high-abundance proteins while the cumulative analysis across multiple spots reveals trace protein information that would be missed in a single-spot analysis.
Solution Approach 2:
The patent transitions from a single-dimensional analysis (one spot) to a multi-dimensional approach by analyzing multiple spots. This dimensional expansion allows the method to simultaneously maintain high-abundance protein detection reliability while uncovering low-abundance proteins through the aggregated data from multiple locations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the detection of proteins in complex biological samples by reducing noise and improving peak definition, enabling the detection of potentially half of all proteins present in serum samples with increased throughput and reliability, beyond the limitations of standard MALDI-TOF instruments.
Implementation Method 1
A laser beam is directed onto a location on the spot for a very brief instant (known as a 'shot'), causing desorption and ionization of molecules or other components of the sample
Implementation Method 2
The instrument measures mass to charge ratio (m/z) and relative intensity of the components (molecules) in the sample in the form of a mass spectrum
Data Source
AI summary
A method of analyzing a biological sample, for example serum or other blood-based samples, using a MALDI-TOF mass spectrometer instrument is described. The method includes the steps of applying the sample to a sample spot on a MALDI-TOF sample plate and directing more than 20,000 laser shots to the sample at the sample spot and collecting mass-spectral data from the instrument. In some embodiments at least 100,000 laser shots and even 500,000 shots are directed onto the sample. It has been discovered that this approach, referred to as “deep-MALDI”, leads to a reduction in the noise level in the mass spectra and that a significant amount of additional spectral information can be obtained from the sample. Moreover, peaks visible at lower number of shots become better defined and allow for more reliable comparisons between samples.